Why is the IT network layout not widely used?

Hi.

Why is the IT network not widely used, since it is much safer than others? I found in google that it is used only where high security is required, e.g. hospitals, and the main disadvantage of this network is the need to constantly monitor the impedance of the system.
Why?
Is it only because of this disadvantage that this network is so rarely used?

Quote:

The IT network system is constantly used in specific solutions, where it is necessary to ensure a high level of protection and ensure its reliability. Most often you can meet him in hospitals, where operating rooms are supplied in this way. This system is characterized by the fact that there is no direct connection to the ground potential from the supply side (the connection is made by high impedance), so there is no path for the short-circuit current. Even if the insulation of the receiving device is damaged, there is no risk of an electric shock. This can only cause a second short-circuit of the next device. The disadvantage of this solution is the necessity to constantly monitor the impedance of the system.

Dzonzi wrote:

Hi.

Why is the IT network not widely used, since it is much safer than others? I found in google that it is used only where high security is required, e.g. hospitals, and the main disadvantage of this network is the need to constantly monitor the impedance of the system.
Why?
Is it only because of this disadvantage that this network is so rarely used?

Yes, that is due to the high construction costs and even higher operating costs.

But reliability compensates for these inconveniences.

Strumien swiadomosci swia wrote:

But reliability compensates for these inconveniences.

Reliability?
TN networks are also reliable, only users fail.

If IT networks existed on a daily basis, repairs would only take place after the second earth fault. The electrician would see how it would not be possible to activate the security.
Where they are subject to supervision, therefore they work as they should.

So what's the deal with impedance control?

The point is to keep it running smoothly.
Originally the network is isolated from "earth". The first earth fault does not matter for her work, it is an advantage. Thanks to this, for example, the respirator works because the fuse has not tripped, but the second earth fault may result in immediate disconnection and the network does not work.
That is why the automation systems control the leakage current and provide timely alarms, thanks to which the first earth fault can be repaired and the network fully operational.

In addition, the network is safe in terms of protection against electric shock, but loses it after the first earth fault. Perhaps I will misuse the term that the network acts like a TN after the first earth fault. Therefore, during the tests, a forced ground fault is performed and the network is tested as TN. Only this earth fault is done with the head so that it would not be a hate.

WojcikW wrote:

Dzonzi wrote:

Why is the IT network not widely used, since it is much safer than others? ...

It is not safer.

Well, how is not safer, since

Quote:

Even if the insulation of the receiving device is damaged, there is no risk of an electric shock

Dzonzi wrote:

Well, how is not safer, since

Quote:

Even if the insulation of the receiving device is damaged, there is no risk of an electric shock

Buddy, because it all depends on one short word. And it is "if."
If the grid is constantly monitored, if the first earth fault is removed immediately (electricians would not be available in the country), if the control devices did not fail (and they are quite complex), if ... if ... if. And finally, the most important thing. If no asshole pushes his fingers into it, which in our country, where there are more misfit electricians than all the inhabitants, is impossible to fulfill. That's the whole problem.

Oh, someone's nerves are gone :D

Because the network is isolated! And the first damage is a misuse of the word safe yet, but each subsequent one is a threat.

Since the network is galvanically isolated from the ground, the only way for electricity is very high resistances and the phenomenon of capacitance.
But with the second earth fault, these resistances can drop to a few k? or several hundred ? and here the path for the shock current is ideal.

I ignore the fact of complicated damage.

This is what the control system is watching to detect.

Yes, we consider damage that is convenient for us, which is one thing. There may be more of them at the same time.
You can also consider grounding the same active conductor in several places at the same time.
Therefore, equalization connections are also important in these networks, but this is a different story.


Consider the operating room.
The surgeon takes the electric saw that is damaged. Saw damaged. The saw is on the table. The earthquake closes the floor table ... now the earthquake is handled is closed by the surgeon but still nothing. But if another fault occurs, the short-circuit path will close between one fault and the other, i.e. the surgeon will be the conductor for the current that will flow between one fault and the other.

There is an operating room, water treatment plants, power plants, individual devices in industrial installations, there are even special inverters for IT networks.


Just so that the device does not fall out of work if something breaks in it.

This is not the case for ordinary clickers and Peciks, which would surely be killed because the first failure would never be removed for various reasons, mainly laziness and dullness.

IT networks are used in coal mines at the bottom with voltages of 500 and 1000 VAC, security measures used UKSI (insulation control device) withdrawn, CZU (central leakage protection) no longer used, RRgzx 0.5 10 central-blocking protection. The first two protections, after lowering the insulation resistance, controlled the network in the voltage state, and RRgzx also controls the network in the de-energized state.

This is what I read and I think that we have a cross-section of IT networks from mining, through hospitals, to Norway, I will add a marine. And yet the assumptions for installing IT networks in these places are quite different. In mining, we use it to avoid the dangers related to the environment, which is often explosive. And hospitals for the acceptance of the first earth fault. In Norway, they use and will be used in wooden houses, which are a phobia of Norwegians, not to burn from the installation. It is known that the return of these installations for houses in Europe is no longer planned, but today's insulation monitoring devices do a great job of dealing with the first earth fault. They disconnect the network at values unmatched by RCDs and do it with much greater certainty.

WojcikW wrote:

New distribution IT is not being built in Norway,

In the city or in remote villages where these houses are built.

I, in turn, am an admirer of my TT. Four wires, not five, EBS (Power Plant) ordered the obligatory use of RCDs, so Chinese electrical traders are rubbing their hands - protection (expensive) and earth rods (even more expensive). But it's strange - the tropics, when mass electrification entered Paramaribo (1930s) and all the buildings then wooden, and the Old Indians say that such a network layout is from the beginning. Probably because the greedy and mean Dutch colonizers were saving on knitting.

WojcikW wrote:

I wonder how the TN system sets fire to wooden houses?

Phase short-circuit to ground or even to N that does not trip by overcurrent. Theoretically possible.

rafal_rx wrote:

WojcikW wrote:

I wonder how the TN system sets fire to wooden houses?

Phase short-circuit to ground or even to N that does not trip by overcurrent. Theoretically possible.

It is enough to use the so-called RCD. fire, i.e. with I? = 300 or even 500 mA.

Maybe the legions of Electricians will stop polemics with lamers because it brings nothing but pointless posts.
There are topics that the Users will never understand, such a world.

IT is space for them.

Depends on requirements. The IT network in the mine is not used to ensure the reliability of the power supply, because at each first earth fault, the power supply is immediately turned off. The most important thing is the low value of the earth leakage current, which in the case of other network systems would be a threat. It is about the so-called fading currents. Let us imagine a mine tunnel which is water-insulated and blasting works are carried out in it, suddenly an earth fault with a high current value may result in the firing of fuses. And also effective shutdown of the power supply as a result of mechanical damage to cables, which is a very common case thanks to the shielded cable, the so-called individual screens for each core and a common screen. When the insulation resistance drops as a result of a fault, the power is immediately disconnected. On the other hand, in hospitals, the most important thing is to ensure the reliability of power supply to operating theaters, and with such small cable capacities, the first earth fault current is 0, so it is not dangerous for humans, which in the case of mines and large capacities of cables from the transformer to the receiver would result in death for humans. In my opinion, it would be the safest at home. With the 400v inter-phase voltage and low operating currents and small cable capacities, the first earth fault would be completely harmless to humans, but due to the cost of the network such as installation and maintenance it is completely unprofitable economically, therefore it is not taken into account at all. Regards

DawidBudny wrote:

Depends on requirements. The IT network in the mine is not used to ensure the reliability of the power supply, because at each first earth fault, the power supply is immediately turned off. The most important thing is the low value of the earth leakage current, which in the case of other network systems would be a threat. It is about the so-called fading currents. Let us imagine a mine tunnel which is water-insulated and blasting works are carried out in it, suddenly an earth fault with a high current value may result in the firing of fuses. And also effective shutdown of the power supply as a result of mechanical damage to cables, which is a very common case
thanks to the shielded cable, the so-called individual screens for each core and a common screen. When the insulation resistance drops as a result of a fault, the power is immediately disconnected. On the other hand, in hospitals, the most important thing is to ensure the reliability of power supply to operating theaters, and with such small cable capacities, the first earth fault current is 0, so it is not dangerous for humans, which in the case of mines and large capacities of cables from the transformer to the receiver would result in death for humans. Regards

It would be good if you were still writing in Polish ...

IT requires special supervision, otherwise it can be dangerous when multiple loads are powered and two of them will break. IT was common in Poland at the beginning of the 20th century, then it was replaced by a safer TT, probably than the French, and during World War II, the Germans began to introduce the TN system in Poland as the safest variant for transmission networks, which did not require such low earth resistance as in TT and at the less susceptible to atmospheric surges due to the multiple earthing points

Strumien swiadomosci swia wrote:

Maybe the legions of Electricians will stop polemics with lamers because it brings nothing but pointless posts.
There are topics that the Users will never understand, such a world.

IT is space for them.

I have learned a lot if someone thinks they know everything or is so haughty that for him the curiosities and basics are nonsense is their problem. Moreover, thanks to the existence of this type of discussion, the search engine advertises the forum, which was not supposed to be a circle of mutual adoration of an important circle of "insiders", but a public value for the exchange of information, help and education.

Such limiting the discussion and throwing negative beliefs stomp, claims that "someone will never understand something" contradicts the idea of a forum, that is communication and education.

It is worth thinking wider than the tip of your nose, coming out of a bubble of limited and negative beliefs about people and the world. Because it HARMs others, poorer the world and life.

Apart from slander, there is probably nothing worse than denying others the right to share their learning, which is like censorship!
If someone does not like the level of the discussion or the questions, let them enter what interests them without spoiling them or impoverishing the interests of others (because it is like vandalism).

As for the topic, I will have the opportunity to help in the implementation of this type of installation at my neighbor and see in practice ew as a passionate doing something similar at home. Because, as I can see in the YT videos, it happens that hobbyists make additional installations themselves, e.g. off-grid, where the electricity does not kick at all, because there is no connection to the ground. Although I am just beginning to implement the topic and I don't know much yet ...

..but everyone has the right to know , in a free world, to learn, to develop. Dividing people and forbidding, limiting them, saying in advance that it is not worth that they will not understand anything is something like a mental terror . Denying people what is most important in civilization that is, access to science, to knowledge!

AdamKurek wrote:

Apart from slander, there is probably nothing worse than denying others the right to share their learning, which is like censorship!

You are already trying to set up others, although this is your first post on the forum. It's polite, yes? Do you have a mirror at home? Take a look. Are you wandering into someone else's yard and doing your cleanup?

AdamKurek wrote:

I learned a lot.
As for the subject, I will have the opportunity to help in the implementation of this type of installation at my neighbor and see for myself in practice

From this it follows that it makes no sense to explain to laymen.
The stream of consciousness was right.

AdamKurek wrote:

Denying people what is most important in civilization, i.e. access to science, to knowledge!

Don't be fairy.
Bookstores are open. Books can be bought.
PKN is also selling willing standards.